Absorption spectroscopy of laser-excited barium

Using a pulsed tunable dye laser either of the 6s6p 1 P 1 0 , 5d6p 3 D 1 0 or 5d6p 3 Pd 1 0 levels in Ba I could be selectively excited from the 6s 2 1 S 0 ground state. A simultaneously pumped broad-band dye laser provided a back-ground continuum for photographic registration of absorption spectra. By quantum defect analysis, series members and perturbing terms of 6sns 1 S 0 were extended from n=9 to n=31, of 6snd 1 D 2 , from n=41 to n=52, and of 6snd 3 D 2 , from n=11 to n=28. In addition, a change of previous assignments is suggested for 6p 2 , 8s, 9s 1 S 0 and 10d, 11d 3 D 2 . Argon or neon was used as a buffer gas. For lines going to levels with high quantum numbers (n>or approximately=12), argon gave a pressure shift to the red of about 0.3 cm -1 per 100 Torr and neon a blue-shift of about 0.015 cm -1 per 100 Torr.